Ronald E. Gerevas has resigned as president...

Ronald E. Gerevas has resigned as president and chief executive of Heidrick & Struggles, a Chicago-based executive search firm. The 52-year old Gerevas, who worked out of the firm’s Los Angeles office, was named president and chief executive of Jenny Craig International of Del Mar, effective Sept. 1. Richard D. Nelson has been named acting chief executive of Heidrick & Struggles until a successor can be selected.